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authorZbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>2014-12-16 23:53:23 -0500
committerZbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>2014-12-18 00:52:41 -0500
commitee05e7795bb9ad7d1212dd49ad362f3e9603c4fd (patch)
tree54b417af3285979aef08af98d50e81b851c9b256 /src/core/main.c
parent503dbda6d94c16161762b7b489677a377f235590 (diff)
core: use raw_clone instead of fork in signal handler
fork() is not async-signal-safe and calling it from the signal handler could result in a deadlock when at_fork() handlers are called. Using the raw clone() syscall sidesteps that problem. The tricky part is that raise() does not work, since getpid() does not work. Add raw_getpid() to get the real pid, and use kill() instead of raise(). https://bugs.freedesktop.org/show_bug.cgi?id=86604
Diffstat (limited to 'src/core/main.c')
-rw-r--r--src/core/main.c25
1 files changed, 15 insertions, 10 deletions
diff --git a/src/core/main.c b/src/core/main.c
index 77980e3929..300567a922 100644
--- a/src/core/main.c
+++ b/src/core/main.c
@@ -142,7 +142,7 @@ noreturn static void crash(int sig) {
/* We want to wait for the core process, hence let's enable SIGCHLD */
sigaction(SIGCHLD, &sa, NULL);
- pid = fork();
+ pid = raw_clone(SIGCHLD, NULL);
if (pid < 0)
log_emergency_errno(errno, "Caught <%s>, cannot fork for core dump: %m", signal_to_string(sig));
@@ -163,11 +163,11 @@ noreturn static void crash(int sig) {
chdir("/");
/* Raise the signal again */
- raise(sig);
+ pid = raw_getpid();
+ kill(pid, sig); /* raise() would kill the parent */
assert_not_reached("We shouldn't be here...");
_exit(1);
-
} else {
siginfo_t status;
int r;
@@ -177,7 +177,13 @@ noreturn static void crash(int sig) {
if (r < 0)
log_emergency_errno(r, "Caught <%s>, waitpid() failed: %m", signal_to_string(sig));
else if (status.si_code != CLD_DUMPED)
- log_emergency("Caught <%s>, core dump failed.", signal_to_string(sig));
+ log_emergency("Caught <%s>, core dump failed (child "PID_FMT", code=%s, status=%i/%s).",
+ signal_to_string(sig),
+ pid, sigchld_code_to_string(status.si_code),
+ status.si_status,
+ strna(status.si_code == CLD_EXITED
+ ? exit_status_to_string(status.si_status, EXIT_STATUS_FULL)
+ : signal_to_string(status.si_status)));
else
log_emergency("Caught <%s>, dumped core as pid "PID_FMT".", signal_to_string(sig), pid);
}
@@ -199,18 +205,17 @@ noreturn static void crash(int sig) {
/* Let the kernel reap children for us */
assert_se(sigaction(SIGCHLD, &sa, NULL) == 0);
- pid = fork();
+ pid = raw_clone(SIGCHLD, NULL);
if (pid < 0)
log_emergency_errno(errno, "Failed to fork off crash shell: %m");
else if (pid == 0) {
make_console_stdio();
- execl("/bin/sh", "/bin/sh", NULL);
+ execle("/bin/sh", "/bin/sh", NULL, environ);
- log_emergency_errno(errno, "execl() failed: %m");
+ log_emergency_errno(errno, "execle() failed: %m");
_exit(1);
- }
-
- log_info("Successfully spawned crash shell as pid "PID_FMT".", pid);
+ } else
+ log_info("Successfully spawned crash shell as PID "PID_FMT".", pid);
}
log_emergency("Freezing execution.");